Costco is the largest membership-only retailer in the United States. It is the third largest retailer in the US and ninth largest in the world. Costco was the first company to grow from zero to $3 billion in revenue in less than six years. Costco's unique retailing approach, called the "treasure hunt," leaves some products in low stock to create urgency for customers. Costco charges annual membership fees between $50-100 and prices products only 15% above its wholesale costs to offer customers trusted low prices.